When a paper jam occurs in an image forming apparatus, toner may be left on components such as a photoconductor, a conveyor belt or an intermediate transfer belt without being transferred onto a sheet. When the density of a transfer image is adjusted in the image forming apparatus, the density pattern is formed on the photoconductor and then transferred onto the conveyor belt for the measurement of its density. In this case, the toner of the density pattern on the conveyor belt needs to be removed after the measurement. A proposed solution to this has been to include a mechanism to remove the toner left on the photoconductor or the like when the paper jam occurs or the toner of the above density pattern, from the photoconductor, the conveyor belt, the intermediate transfer belt, or the like, and to collect the toner in the waste toner container.
When the image forming is continuously performed even after the toner collected in the toner container reaches the maximum storage level, the waste toner cannot be collected appropriately. This may cause a toner leakage, resulting in malfunction in the image forming apparatus.
The image forming apparatus disclosed in Japanese Patent Application Publication No. JP-A-2004-101667 is designed to stop the image forming operation when the waste toner collected in the toner container (waste toner box) reaches the maximum storage level so as to prevent the toner leakage or the like that causes malfunction in the image forming apparatus.
Once the waste toner collected in the toner container reaches the maximum storage level, further image forming operation thereafter is undesirable, and therefore, the operation has to be stopped. If the timing at which the waste toner is about to reach the maximum storage level is known to the user in advance, it is possible for the user to try to delay the timing at which the waste toner collected in the toner container reaches the maximum storage level by reducing the number of the image forming operations so that the image forming apparatus can be used as long as possible. However, this may put a considerable strain on the user.
In view of the aforementioned circumstances, there is a need for a technique that delays the timing at which the waste toner collected in the toner container of the image forming apparatus reaches the maximum storage level without increasing the strain on the user.